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freebsd-dev/sys/dev/xen/control/control.c
John Baldwin fdce57a042 Add an EARLY_AP_STARTUP option to start APs earlier during boot. 
Currently, Application Processors (non-boot CPUs) are started by
MD code at SI_SUB_CPU, but they are kept waiting in a "pen" until
SI_SUB_SMP at which point they are released to run kernel threads.
SI_SUB_SMP is one of the last SYSINIT levels, so APs don't enter
the scheduler and start running threads until fairly late in the
boot.

This change moves SI_SUB_SMP up to just before software interrupt
threads are created allowing the APs to start executing kernel
threads much sooner (before any devices are probed).  This allows
several initialization routines that need to perform initialization
on all CPUs to now perform that initialization in one step rather
than having to defer the AP initialization to a second SYSINIT run
at SI_SUB_SMP.  It also permits all CPUs to be available for
handling interrupts before any devices are probed.

This last feature fixes a problem on with interrupt vector exhaustion.
Specifically, in the old model all device interrupts were routed
onto the boot CPU during boot.  Later after the APs were released at
SI_SUB_SMP, interrupts were redistributed across all CPUs.

However, several drivers for multiqueue hardware allocate N interrupts
per CPU in the system.  In a system with many CPUs, just a few drivers
doing this could exhaust the available pool of interrupt vectors on
the boot CPU as each driver was allocating N * mp_ncpu vectors on the
boot CPU.  Now, drivers will allocate interrupts on their desired CPUs
during boot meaning that only N interrupts are allocated from the boot
CPU instead of N * mp_ncpu.

Some other bits of code can also be simplified as smp_started is
now true much earlier and will now always be true for these bits of
code.  This removes the need to treat the single-CPU boot environment
as a special case.

As a transition aid, the new behavior is available under a new kernel
option (EARLY_AP_STARTUP).  This will allow the option to be turned off
if need be during initial testing.  I plan to enable this on x86 by
default in a followup commit in the next few days and to have all
platforms moved over before 11.0.  Once the transition is complete,
the option will be removed along with the !EARLY_AP_STARTUP code.

These changes have only been tested on x86.  Other platform maintainers
are encouraged to port their architectures over as well.  The main
things to check for are any uses of smp_started in MD code that can be
simplified and SI_SUB_SMP SYSINITs in MD code that can be removed in
the EARLY_AP_STARTUP case (e.g. the interrupt shuffling).

PR:		kern/199321
Reviewed by:	markj, gnn, kib
Sponsored by:	Netflix
2016-05-14 18:22:52 +00:00

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/*-
* Copyright (c) 2010 Justin T. Gibbs, Spectra Logic Corporation
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions, and the following disclaimer,
* without modification.
* 2. Redistributions in binary form must reproduce at minimum a disclaimer
* substantially similar to the "NO WARRANTY" disclaimer below
* ("Disclaimer") and any redistribution must be conditioned upon
* including a substantially similar Disclaimer requirement for further
* binary redistribution.
*
* NO WARRANTY
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
* IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGES.
*/
/*-
* PV suspend/resume support:
*
* Copyright (c) 2004 Christian Limpach.
* Copyright (c) 2004-2006,2008 Kip Macy
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by Christian Limpach.
* 4. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/*-
* HVM suspend/resume support:
*
* Copyright (c) 2008 Citrix Systems, Inc.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
/**
* \file control.c
*
* \brief Device driver to repond to control domain events that impact
* this VM.
*/
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/bio.h>
#include <sys/bus.h>
#include <sys/conf.h>
#include <sys/disk.h>
#include <sys/fcntl.h>
#include <sys/filedesc.h>
#include <sys/kdb.h>
#include <sys/module.h>
#include <sys/namei.h>
#include <sys/proc.h>
#include <sys/reboot.h>
#include <sys/rman.h>
#include <sys/sched.h>
#include <sys/taskqueue.h>
#include <sys/types.h>
#include <sys/vnode.h>
#include <sys/sched.h>
#include <sys/smp.h>
#include <sys/eventhandler.h>
#include <sys/timetc.h>
#include <geom/geom.h>
#include <machine/_inttypes.h>
#include <machine/intr_machdep.h>
#include <x86/apicvar.h>
#include <vm/vm.h>
#include <vm/vm_extern.h>
#include <vm/vm_kern.h>
#include <xen/xen-os.h>
#include <xen/blkif.h>
#include <xen/evtchn.h>
#include <xen/gnttab.h>
#include <xen/xen_intr.h>
#include <xen/hvm.h>
#include <xen/interface/event_channel.h>
#include <xen/interface/grant_table.h>
#include <xen/xenbus/xenbusvar.h>
/*--------------------------- Forward Declarations --------------------------*/
/** Function signature for shutdown event handlers. */
typedef void (xctrl_shutdown_handler_t)(void);
static xctrl_shutdown_handler_t xctrl_poweroff;
static xctrl_shutdown_handler_t xctrl_reboot;
static xctrl_shutdown_handler_t xctrl_suspend;
static xctrl_shutdown_handler_t xctrl_crash;
/*-------------------------- Private Data Structures -------------------------*/
/** Element type for lookup table of event name to handler. */
struct xctrl_shutdown_reason {
const char *name;
xctrl_shutdown_handler_t *handler;
};
/** Lookup table for shutdown event name to handler. */
static const struct xctrl_shutdown_reason xctrl_shutdown_reasons[] = {
{ "poweroff", xctrl_poweroff },
{ "reboot", xctrl_reboot },
{ "suspend", xctrl_suspend },
{ "crash", xctrl_crash },
{ "halt", xctrl_poweroff },
};
struct xctrl_softc {
struct xs_watch xctrl_watch;
};
/*------------------------------ Event Handlers ------------------------------*/
static void
xctrl_poweroff()
{
shutdown_nice(RB_POWEROFF|RB_HALT);
}
static void
xctrl_reboot()
{
shutdown_nice(0);
}
static void
xctrl_suspend()
{
#ifdef SMP
cpuset_t cpu_suspend_map;
#endif
int suspend_cancelled;
EVENTHANDLER_INVOKE(power_suspend_early);
stop_all_proc();
EVENTHANDLER_INVOKE(power_suspend);
#ifdef EARLY_AP_STARTUP
MPASS(mp_ncpus == 1 || smp_started);
thread_lock(curthread);
sched_bind(curthread, 0);
thread_unlock(curthread);
#else
if (smp_started) {
thread_lock(curthread);
sched_bind(curthread, 0);
thread_unlock(curthread);
}
#endif
KASSERT((PCPU_GET(cpuid) == 0), ("Not running on CPU#0"));
/*
* Clear our XenStore node so the toolstack knows we are
* responding to the suspend request.
*/
xs_write(XST_NIL, "control", "shutdown", "");
/*
* Be sure to hold Giant across DEVICE_SUSPEND/RESUME since non-MPSAFE
* drivers need this.
*/
mtx_lock(&Giant);
if (DEVICE_SUSPEND(root_bus) != 0) {
mtx_unlock(&Giant);
printf("%s: device_suspend failed\n", __func__);
return;
}
#ifdef SMP
#ifdef EARLY_AP_STARTUP
/*
* Suspend other CPUs. This prevents IPIs while we
* are resuming, and will allow us to reset per-cpu
* vcpu_info on resume.
*/
cpu_suspend_map = all_cpus;
CPU_CLR(PCPU_GET(cpuid), &cpu_suspend_map);
if (!CPU_EMPTY(&cpu_suspend_map))
suspend_cpus(cpu_suspend_map);
#else
CPU_ZERO(&cpu_suspend_map); /* silence gcc */
if (smp_started) {
/*
* Suspend other CPUs. This prevents IPIs while we
* are resuming, and will allow us to reset per-cpu
* vcpu_info on resume.
*/
cpu_suspend_map = all_cpus;
CPU_CLR(PCPU_GET(cpuid), &cpu_suspend_map);
if (!CPU_EMPTY(&cpu_suspend_map))
suspend_cpus(cpu_suspend_map);
}
#endif
#endif
/*
* Prevent any races with evtchn_interrupt() handler.
*/
disable_intr();
intr_suspend();
xen_hvm_suspend();
suspend_cancelled = HYPERVISOR_suspend(0);
xen_hvm_resume(suspend_cancelled != 0);
intr_resume(suspend_cancelled != 0);
enable_intr();
/*
* Reset grant table info.
*/
gnttab_resume(NULL);
#ifdef SMP
if (!CPU_EMPTY(&cpu_suspend_map)) {
/*
* Now that event channels have been initialized,
* resume CPUs.
*/
resume_cpus(cpu_suspend_map);
/* Send an IPI_BITMAP in case there are pending bitmap IPIs. */
lapic_ipi_vectored(IPI_BITMAP_VECTOR, APIC_IPI_DEST_ALL);
}
#endif
/*
* FreeBSD really needs to add DEVICE_SUSPEND_CANCEL or
* similar.
*/
DEVICE_RESUME(root_bus);
mtx_unlock(&Giant);
/*
* Warm up timecounter again and reset system clock.
*/
timecounter->tc_get_timecount(timecounter);
timecounter->tc_get_timecount(timecounter);
inittodr(time_second);
#ifdef EARLY_AP_STARTUP
thread_lock(curthread);
sched_unbind(curthread);
thread_unlock(curthread);
#else
if (smp_started) {
thread_lock(curthread);
sched_unbind(curthread);
thread_unlock(curthread);
}
#endif
resume_all_proc();
EVENTHANDLER_INVOKE(power_resume);
if (bootverbose)
printf("System resumed after suspension\n");
}
static void
xctrl_crash()
{
panic("Xen directed crash");
}
static void
xen_pv_shutdown_final(void *arg, int howto)
{
/*
* Inform the hypervisor that shutdown is complete.
* This is not necessary in HVM domains since Xen
* emulates ACPI in that mode and FreeBSD's ACPI
* support will request this transition.
*/
if (howto & (RB_HALT | RB_POWEROFF))
HYPERVISOR_shutdown(SHUTDOWN_poweroff);
else
HYPERVISOR_shutdown(SHUTDOWN_reboot);
}
/*------------------------------ Event Reception -----------------------------*/
static void
xctrl_on_watch_event(struct xs_watch *watch, const char **vec, unsigned int len)
{
const struct xctrl_shutdown_reason *reason;
const struct xctrl_shutdown_reason *last_reason;
char *result;
int error;
int result_len;
error = xs_read(XST_NIL, "control", "shutdown",
&result_len, (void **)&result);
if (error != 0)
return;
reason = xctrl_shutdown_reasons;
last_reason = reason + nitems(xctrl_shutdown_reasons);
while (reason < last_reason) {
if (!strcmp(result, reason->name)) {
reason->handler();
break;
}
reason++;
}
free(result, M_XENSTORE);
}
/*------------------ Private Device Attachment Functions --------------------*/
/**
* \brief Identify instances of this device type in the system.
*
* \param driver The driver performing this identify action.
* \param parent The NewBus parent device for any devices this method adds.
*/
static void
xctrl_identify(driver_t *driver __unused, device_t parent)
{
/*
* A single device instance for our driver is always present
* in a system operating under Xen.
*/
BUS_ADD_CHILD(parent, 0, driver->name, 0);
}
/**
* \brief Probe for the existence of the Xen Control device
*
* \param dev NewBus device_t for this Xen control instance.
*
* \return Always returns 0 indicating success.
*/
static int
xctrl_probe(device_t dev)
{
device_set_desc(dev, "Xen Control Device");
return (BUS_PROBE_NOWILDCARD);
}
/**
* \brief Attach the Xen control device.
*
* \param dev NewBus device_t for this Xen control instance.
*
* \return On success, 0. Otherwise an errno value indicating the
* type of failure.
*/
static int
xctrl_attach(device_t dev)
{
struct xctrl_softc *xctrl;
xctrl = device_get_softc(dev);
/* Activate watch */
xctrl->xctrl_watch.node = "control/shutdown";
xctrl->xctrl_watch.callback = xctrl_on_watch_event;
xctrl->xctrl_watch.callback_data = (uintptr_t)xctrl;
xs_register_watch(&xctrl->xctrl_watch);
if (xen_pv_domain())
EVENTHANDLER_REGISTER(shutdown_final, xen_pv_shutdown_final, NULL,
SHUTDOWN_PRI_LAST);
return (0);
}
/**
* \brief Detach the Xen control device.
*
* \param dev NewBus device_t for this Xen control device instance.
*
* \return On success, 0. Otherwise an errno value indicating the
* type of failure.
*/
static int
xctrl_detach(device_t dev)
{
struct xctrl_softc *xctrl;
xctrl = device_get_softc(dev);
/* Release watch */
xs_unregister_watch(&xctrl->xctrl_watch);
return (0);
}
/*-------------------- Private Device Attachment Data -----------------------*/
static device_method_t xctrl_methods[] = {
/* Device interface */
DEVMETHOD(device_identify, xctrl_identify),
DEVMETHOD(device_probe, xctrl_probe),
DEVMETHOD(device_attach, xctrl_attach),
DEVMETHOD(device_detach, xctrl_detach),
DEVMETHOD_END
};
DEFINE_CLASS_0(xctrl, xctrl_driver, xctrl_methods, sizeof(struct xctrl_softc));
devclass_t xctrl_devclass;
DRIVER_MODULE(xctrl, xenstore, xctrl_driver, xctrl_devclass, NULL, NULL);
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